Vauxhall Corsa car won't pull off and it will only accelarate

I have been having trouble with my car, one day i was driving along to work in the morning and suddenly the car just lost power and eventually got it into a slip road, and that day i had to tow it home. but ever since then the car hasnt pulled off. there is no biting point what so ever, i can rev the car but it just won't pull of. what could the problem be? any help would be appreciated. thanks